Transfer conveyors

ABSTRACT

In a conveyor wherein load carrying trolleys are normally propelled along a fixed trolley track by pusher dogs which depend from an endless driven chain disposed above such track there is provided a transfer unit for moving load carrying trolleys along any section of said trolley track above which there is no endless chain. The transfer unit, which is supported for movement along a path parallel with any such section of track includes reversible drive means whereby a drive may be imparted thereto in either direction and a laterally directed arm which is adapted to project into the path of any load carrying trolley present on such section of track and is effective on movement of the unit in one direction to propel such trolley. It is also envisaged that the transfer unit will be employed for transferring load carrying trolleys from the trolley track of one conveyor to the trolley track of a second conveyor and in such a case the trolley tracks of the two conveyors will be interconnected by means of a transfer track and the transfer unit will be arranged to move back and forth along a path parallel to said transfer track.

llnited States Patent [1 1 Wilkinson July 3, 1973 TRANSFER CONVEYORS Primary Examiner-Gerald M. Forlenza [75] Inventor: Keith Wilkinson, Stevenage, Ass'smm r t- He tf d hi England Attorney-Eric H. Waters, John G. Schwartz et al. [73] Assignee: Geo. W. King Limited, Stevenage,

England [57] ABSTRACT [22] Filed; N 4, 1971 In a conveyor wherein load carrying trolleys are normally propelled along a fixed trolley track by pusher [21] Appl' 195621 dogs which depend from an endless driven chain dis- R Iated [1,5, A li ti D t posed above such tracl there is provided a transfer unit [63] Continuation of Ser. No. 10391, Feb 11 1970, for moving load carrying trolleys along any section of abandoned said trolley track above which there is no endless chain. The transfer unit, which is supported for movement [30] Foreign Application Priority Data along a path parallel with any such section of track ineludes reversible drive means whereby a drive may be Feb. 18, 1969 Great Britain 8,840/69 imparted thereto in either direction a a laterally di [52] U S C] 104/96 104/162 104/172 S rected arm which is adapted to project into the path of [51] B6lb 3/02 i 17/42 any load carrying trolley present on such section of 58] Field 104/96 17288 162 track and is effective on movement of the unit in one 1 021/1 direction to propel such trolley. It is also envisaged that the transfer unit will be employed for transferring load 5 References Cited carrying trolleys from the trolley track of one conveyor to the trolley track of a second conveyor and in such UNITED STATES PATENTS a case the trolley tracks of the two conveyors will be in- 3,242,875 3/1966 BUHOWS l04/96 te -connected by means of a transfgr track and the 3,523,504 8/1970 Jones l04/l72 S transfer unit will be arranged to move back and f h along a path parallel to said transfer track.

3 Claims, 7 Drawing Figures PATENTEDJULS 1915' 3 742 861 sum 0F 6 .4 M EC k (Mala Q m 1 W w M; Z

PATENTED JUL 3 I975 SHEET 2 BF 6 PAIENIEDJUL3 I975 saw 3 BF 6 llllilllllll FIG. 3

TRANSFER CONVEYORS CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation of application Ser. No. 10,391 filed Feb. 11, 1970, now abandoned.

This invention relates to conveyor systems including two conveyors each of the kind wherein load carrying trolleys are propelled along a fixed load trolley track by virtue of the engagement therewith of pusher or drive dogs which depend from an endless driven chain disposed vertically above said fixed track.

It is an object of the invention to provide means whereby it will be possible, in cases where the paths of two conveyors of the kind indicated are arranged in proximity, to effect transfer of load trolleys from one conveyor to the other.

According to the present invention, there is provided in a conveyor system including two conveyors each of the kind wherein load carrying trolleys are normally continuously propelled along a trolley track by pusher dogs depending from an endless driven chain disposed above such track, the provision of means for transferring load carrying trolleys from the trolley track of one conveyor to the trolley track of the second conveyor such means comprising a transfer track connecting the trolley tracks of the two conveyors, switch means operable at will to divert any selected load carrying trolley from the trolley track of said one conveyor on to said transfer track, a transfer unit, supporting means extending parallel to said transfer track and supporting said transfer unit in movement back and forth along a path parallel to the transfer track, said unit comprising reversible drive means whereby a drive may be imparted thereto in either direction at will and a laterally projecting arm which is arranged to project into the path of any trolley present on said transfer track and is effective on movement of said unit in a direction towards the second conveyor to propel the load trolley along said transfer track and on to the trolley track of the second conveyor, said reversible drive means comprising a reversible electric motor arranged to drive a drive wheel in turn arranged to co-operate with a fixed element such that rotation of said drive wheel in one direction or the other will result in movement of the unit back or forth along said path parallel to said transfer track, and means provided such that a selected load carrying trolley is propelled by said unit along said transfer track into a position out of the paths of move ment of the load carrying trolleys of the first and second conveyors and remains in that position until the approach of a free pusher dog on the chain of the secondconveyor causes said unit to propel the selected load carrying trolley onto the trolley track of the second conveyor so that the trolley is engaged by the free pusher dog.

In order that the said invention may be clearly understood and readily carried into effect the same will be hereinafter more fully described with reference to the accompanying drawings in which:

FIG. 1 is a perspective view of a small part of a conveyor of the kind with which the invention is concerned,

FIG. 2 is a diagrammatic plan view illustrating a possible layout for effecting transfer of load trolleys from one conveyor to another,

FIG. 3 is a plan view illustrating a portion of a transfer track and its junction with the trolley track of a conveyor to which load trolleys are to be transferred, a transfer unit being also indicated together with a portion of the track on which such unit travels,

FIGS. 4, 5 and 6 are respectively a side elevational, plan view and end elevational view'of a transfer unit,

FIG. 7 is a section on the line 88 of FIG. 3 and illustrates the relative disposition of the track for the transfer unit and of the tracks for the load and chain trolleys of a conveyor.

Referring initially to FIG. 1 which illustrates diagrammatically a small section of a conveyor of the kind with which the invention is concerned, 10 denotes a oad carrying trolley which is equipped with a depending load bar 11 from which loads to be conveyed are suspended. Load carrying trolleys such as that indicated at 10 are propelled along a fixed track 12, hereinafter termed the trolley track, by means of an endless driven chain 13 which is supported at spaced points along its length by means of so-called chain trolleys one of which is indicated at 14. The chain trolleys run on a second fixed track 16, hereinafter termed the chain trolley track, disposed vertically above the track 12. The chain 13 is provided at spaced points along its length with depending pusher dogs 17 which are adapted to cooperate with upstanding driving abutments on the load carrying trolleys 10 the arrangement being such that on a drive being imparted to the chain 13 the dogs 17 will by virtue of their engagement with the abutments on the trolleys 10 cause the latter to be propelled along the track 12. In the embodiment illustrated l8 denotes the driving abutment on the trolley 10.

In known manner each trolley is equipped with an upstanding retainer abutment 19 which will be effective to prevent uncontrolled forward movement of said trolleys relatively to the chain 13. To allow for indexing of load trolleys, i.e., for stoppage of such trolleys at one or more selected points along the conveyor path without any interruption of the drive to the chain 13, the drive abutment 18 on each trolley is so mounted as to be capable of retraction into a position wherein it will lie out of the path of the pusher dogs 17 on the chain. The retainer abutment 19 on each trolley 10 is so mounted that while being free to pivot forwardly, i.e., in the direction of travel of the trolley it will be held against movement past the vertical position in a rearward direction. As indicated conveyors of the kind indicated above are generally well known and further description thereof is not considered necessary.

It is an object of the present invention to provide means whereby load carrying trolleys may be trans ferred from the trolley track of one conveyor of the kind indicated to the trolley track of a second similar conveyor.

In FIG. 2, 21 denotes a conveyor of the kind indicated along which load carrying trolleys are propelled in the direction indicated by the arrows. 22 denotes a second similar conveyor to which load trolleys from the conveyor 21 are to be transferred. To effect such transfer a transfer track 23 is provided, there being a switch tongue of known type at the confluence of the trolley track of the conveyor 21 and of the transfer track 23 so that when any trolley is to be transferred it will, on operation of the switch tongue, be diverted from the trolley track of the conveyor 21 to the transfer track 23. A similar switch tongue of known type is also provided at the confluence of the transfer track 23 with the trolley track of the second conveyor 22 so that any trolley present on said transfer track may be moved on to the trolley track of said conveyor 22. In FIG. 3 there is illustrated one suitable form of switch tongue 24 which is installed at the confluence of the transfer track 23 and of the trolley track of the conveyor 22. The switch tongue illustrated in FIG. 3 is purely exemplary and any apropriate form of switch device may be employed. The switch tongues or devices employed may be operated manually or mechanically and/or electrically in accordance with common practice in the conveyor art.

To effect movement of the trolleys along the transfer track 23 a mobile transfer unit designated generally by 25 is provided such unit being adapted to travel back and forth along a track 26 which is disposed alongside and parallel to the track 23. As will be clearly seen from FIGS. 3 and 7 the track 26 comprises two parallel rails each made up of lengths of channel section members such rails being supported at spaced points along their length by means of brackets such as 27 (FIGS. 3 and 7) which are attached to brackets 28 carried by the conveyor trolley tracks and the transfer track.

The transfer unit 25 is equipped with a reversible electric motor 28' which is adapted on operation to drive a sprocket 29 via a coupling 30 and a worm reduction gear 31. At its upper part the unit is equipped with three freely rotatable rollers 32 which are adapted to be engaged and to run in the track 26 so as to support said unit for travel back and forth along said track. The arrangement is such that with the unit in position on the track 26 the sprocket 29 will mesh with a roller chain 33 fixedly mounted on the inside of one of the rails forming said track as indicated in FIG. 7. Instead of a roller chain it may be preferred to provide a toothed rack with which the sprocket 29 can mesh. It will be appreciated that with the transfer unit in position on the track 26 and with the sprocket 29 engaged with the chain or rack 33 operation of the motor 28' in one direction or the other will result in movement of said unit along the track 26 in one direction or the other. Pivotally mounted at the underside of the unit is an arm 34 which is adapted when in the operative position shown in FIG. 3 to project across the underside of the transfer track 23 into the path of the lower part of any load carrying trolley which may be present on said transfer track. The arm 34 which is pivoted at 35 is normally held by a spring 36 so that one end thereof will abut against a stop 37, the arrangement being such that while said arm is capable of pivotal movement in one direction as indicated by the arrow A in FIG. 3 it will be prevented by the stop from moving from its operative position in the opposite direction. Preferably as indicated at 38, FIGS. 3 and 5, the outer end of the arm 34 will be chamfered, the purpose of such chamfering being hereinafter made apparent.

It is envisaged that the layout such as is indicated in FIG. 2 will operate in the following manner.

In normal circumstances the mobile transfer unit 25 will assume an at rest position on its track 26 some way along the transfer track 23 wherein it will be clear of any trolleys passing along the trolley track of the first conveyor 21. In FIG. 2 the at rest position of the transfer unit is indicated at B.

When a selected trolley is to be transferred from the conveyor 21 the track switch will be operated as such trolley approaches thereby to effect diversion of the trolley on to the transfer track 23. If the track switch is electrically operated actuation of said switch will be initiated by closure of a limit switch 39 disposed along the path of the conveyor 21 and actuated by a selector carried by the trolley. As the trolley passes off the trolley track of the conveyor 21, it, or a member associated therewith will actuate a limit switch 40 thereby to cause energization of the motor 28 of the transfer unit 25 in a direction such that said unit will be driven from its at rest position towards the conveyor 21. As the transfer unit moves the arm 34 will contact the lower part of the waiting trolley and will as a result merely pivot idly thus brushing past said trolley. The chamfering 38 on the arm 34 will facilitate such pivoted movement of said arm. The transfer unit continues to move until it reaches a position wherein the arm 34 will be restored by the spring 36 to its operative position against the stop 37 and will be located behind the lower part of the waiting trolley. At this point the transfer unit will contact a limit switch 43 which will reverse the direction of the transfer unit. The arm 34 which is then maintained rigid by virtue of its abutment against the stop 37, will contact the lower part of the load trolley and propel the latter along the transfer track 23 to point B rest position where any suspended load on the load trolley will be clear of following loads on conveyor 21, or passing loads on conveyor 22. At this point the transfer unit 25 will be halted and it will remain stationary until it receives an appropriate signal from the second conveyor 22. The arrangement will be such that as the free pusher dog on the driven chain of the second conveyor 22 approaches the transfer zone a limit switch 41 disposed adjacent said second conveyor will be closed to energize the motor 28' of the transfer unit thereby to cause the latter to move along the track 26 parallel to the transfer track 23 towards the load trolley track of the second conveyor 22. This movement will continue until the trolley is so positioned on the trolley track of the second conveyor 22 that its drive abutment will be in position to be contacted by the approaching free pusher dog on the driven chain of said second conveyor. The arrangement will be such that as the transfer unit approaches the end of its travel it will actuate a further limit switch 42 which will be effective to cause stoppage of said unit and subsequent reverse movement thereof back to its at rest position in readiness for a further operation. As a safety precaution some sort of positive stop means may be provided positively to stop the transfer unit at the limit of its travel towards the second conveyor 22.

Instead of equipping the transfer unit with a drive sprocket such as 29 it may be feasible to replace such sprocket by a drive wheel which is coated with friction material such as polyurethane. In such a case the roller chain or rack 33 would be replaced by a strip formed of or appropriately coated with a friction gripping material.

I claim:

1. In a conveyor system including two conveyors each of the kind wherein load carrying trolleys are normally continuously propelled along a trolley track by pusher dogs depending from an endless driven chain disposed above such track, the provision of means for transferring load carrying trolleys from the trolley track of one conveyor to the trolley track of the second conveyor, said means comprising a transfer track connecting the trolley tracks of the two conveyors, switch means operable at will to divert any selected load carrying trolley from the trolley track of said one conveyor on to said transfer track, a transfer unit, supporting means extending parallel to said transfer track and supporting said transfer unit for movement back and forth along a path parallel to the transfer track, said transfer unit comprising reversible drive means whereby a drive may be imparted thereto in either direction at will and a laterally projecting arm which is arranged to project into the path of any trolley present on said transfer track and is effective on movement of said unit in a direction towards the second conveyor to propel the load trolley along said transfer track and on to the trolley track of the second conveyor, said reversible drive means comprising a drive wheel arranged to cooperate with a fixed element, a reversible electric motor arranged to drive said drive wheel such that rotation of said drive wheel in one direction or the other will result in movement of the unit back or forth along said path parallel to said transfer track, and means enabling a selected load carrying trolley to be propelled by said unit along said transfer track into a position out of the paths of movement of the load carrying trolleys of the first and second conveyors and remain in that position until the approach of a free pusher dog on the chain of the second conveyor causes said unit to propel the selected load carrying trolley onto the trolley track of the second conveyor so that the trolley is engaged by the free pusher dog. 7

2. A conveyor system according to claim 1, wherein the last-mentioned means is operative such that, on diversion of a load carrying trolley onto the transfer track, the transfer unit will be moved automatically from an initial position out of said paths of movement and intermediate the ends of said transfer track to a position wherein it will be effective subsequently to propel said trolley.

3. A conveyor system according to claim 1, wherein said arm is pivotally mounted on the transfer unit and is spring loaded to assume an operative position, the arrangement being such that while said arm is capable of free pivotal movement in one direction from its operative position, pivotal movement in the other direction from 'said operative position will be prevented. 

1. In a conveyor system including two conveyors each of the kind wherein load carrying trolleys are normally continuously propelled along a trolley track by pusher dogs depending from an endless driven chain disposed above such track, the provision of means for transferring load carrying trolleys from the trolley track of one conveyor to the trolley track of the second conveyor, said means comprising a transfer track connecting the trolley tracks of the two conveyors, switch means operable at will to divert any selected load carrying trolley from the trolley track of said one conveyor on to said transfer track, a transfer unit, supporting means extending parallel to said transfer track and supporting said transfer unit for movement back and forth along a path parallEl to the transfer track, said transfer unit comprising reversible drive means whereby a drive may be imparted thereto in either direction at will and a laterally projecting arm which is arranged to project into the path of any trolley present on said transfer track and is effective on movement of said unit in a direction towards the second conveyor to propel the load trolley along said transfer track and on to the trolley track of the second conveyor, said reversible drive means comprising a drive wheel arranged to cooperate with a fixed element, a reversible electric motor arranged to drive said drive wheel such that rotation of said drive wheel in one direction or the other will result in movement of the unit back or forth along said path parallel to said transfer track, and means enabling a selected load carrying trolley to be propelled by said unit along said transfer track into a position out of the paths of movement of the load carrying trolleys of the first and second conveyors and remain in that position until the approach of a free pusher dog on the chain of the second conveyor causes said unit to propel the selected load carrying trolley onto the trolley track of the second conveyor so that the trolley is engaged by the free pusher dog.
 2. A conveyor system according to claim 1, wherein the last-mentioned means is operative such that, on diversion of a load carrying trolley onto the transfer track, the transfer unit will be moved automatically from an initial position out of said paths of movement and intermediate the ends of said transfer track to a position wherein it will be effective subsequently to propel said trolley.
 3. A conveyor system according to claim 1, wherein said arm is pivotally mounted on the transfer unit and is spring loaded to assume an operative position, the arrangement being such that while said arm is capable of free pivotal movement in one direction from its operative position, pivotal movement in the other direction from said operative position will be prevented. 